On 19 July 2015 at 06:40, Igor R <boost.li...@gmail.com> wrote: >>> On x86 one can get the current PGD from CR3. What's the right way to >>> do this on ARM? >> >> What's a PGD ? > > Page global directory
That doesn't help much -- I don't know x86 terminology and it's not an ARM term. >>> But in the recent QEMU version c2_base0 field is absent. Instead, >>> there's ttbr0[] array. So should I just use ttbr0[current_el]? >> >> What are you trying to do inside QEMU with the page tables? > > When debugging (via gdbstub), I would like to get the current process > id by a virtual address. When the virtual address is in the > user-space, the only way to find the current task_struct I can think > of is to iterate over all the task_struct's (assuming we know > task_init and the offsets of the relevant fields), and compare > task->mm->pgd against the current PGD. If your kernel is configured with CONFIG_PID_IN_CONTEXTIDR you can just read the PID out of CONTEXTIDR, which will be much simpler. (You'd need to expose the contextidr via gdbstub somehow, but then you'd need to do something in QEMU to get at the TTBRs too.) -- PMM
